Monitoring Ute Ladiesi-tresses {Spiranthes diluvialis\ in Jefferson County, Montana Final Report, 1996-2000 Prepared for: Bureau of Land Management State Office and Butte Field Office Prepared by: Bonnie Heidel June 2001 U f> N T A K A ^ Natural Heritage Z*^ Program Monitoring Ute Ladiesi-tresses {Spiranthes diluvialis\ in Jefferson County, Montana Final Report, 1996-2000 © 2001 Montana Natural Heritage Program state Library Building • P.O. Box 20 1 800 • 1 5 1 5 East Sixth Avenue • Helena, MX 59620- 1 800 • 406-444-3009 Agreement No. 1422E930A960015 Task Order No. 23 For Bureau of Land Management State Office and Butte Field Office P.O. Box 3388 Butte, MT 59702-3388 This document should be cited as follows: Heidel, B. 2001 . Monitoring Ute Ladiesi-tresses {Spiranthes diluvialis), in Jefferson County, Montana, 1996-2000. Report to Bureau of Land Management. Montana Natural Heritage Program, Helena. 10pp. + app. Executive Summary We monitored one population of Ute ladiesi- tresses {Spiranthes diluvialis), a wetland plant designated as threatened under the Endangered Species Act, in order to: • help interpret the results of baseline surveys, • provide preliminarily assessment of population trend, • identify critical life history stages, and • guide future management actions. Rigorous trend analysis and identification of critical life history stages were not possible because we had only two-to-three years of data on the isea- sonally-dormanti stage. This stage remains underground throughout the entire growing season and cannot be discerned from plant mortality except after dormancy duration and mortality rates have been calculated. Prelimi- nary analysis indicates that season-long dormancy exceeds two years. Management recommendations include avoiding direct impact to the flowering stage, providing annual or periodic reduction in competing vegetation, and conducting multi- year monitoring to evaluate any management action changes. Acknowledgements This monitoring study began as a task added It was continued for two of the following three to the Spiranthes diluvialis status survey years under Bureau of Land Management chal- supported under the U. S . Fish and Wildlife lenge cost-share agreements with the Montana Service Section 6 cooperative agreement with Natural Heritage Program. Landowner access the Montana State Library through its Mon- permission and coordination are also acknowl- tana Natural Heritage Program. edged with appreciation. Table of Contents Introduction 1 Species Background 1 Habitat and Study Site 4 Methods 5 Results and Discussion 6 Life History and Trend 7 Comparison with Other Monitoring Studies 8 Guide to Future Management Action 10 Literature Cited 11 FIGURES Figure I. llhistration of Spiranthes diluvialis 1 Figure 2. Photograph of 5)9/ra/7^/z^^(i/7z/v/afo in flower 2 Figure 3. Photograph of5y9zraf2^/2^^(i/7i^v/afo in vegetative stage 2 Figure 4. Life history of Spiranthes diluvialis 3 Figure 5. Photograph of study site 4 Figure 6. Climate of Twin Bridges, MT 5 Figure?. Monitoring overview of 5/7/ra^//ze^(i/7i/v/(2fo 7 Figure 8. Dormancy duration of 5/7/ra/7^/z^^(i/7z/v/afo 9 Figure 9. Vegetative stage duration of 5p/ra/7^/ze^ (7/7i^v/afo 9 Figure 10. Flowering stage duration of 5/7/ra^^/z^^J/7z/v/afo 9 Appendix A. Global and State Rank Guidelines m Introduction Species Background Ute ladiesi-tresses {Spiranthes diluvialis) is a wetland plant designated as threatened under the Endangered Species Act (Federal Register 1 992). It was first documented in Montana in 1 994, at the northern end of its range (Heidel 1 996, 1 998). This report describes demo- graphic monitoring begun in 1 996 to help interpret the results of baseline surveys, identify critical life history stages, assess population trend, and guide future manage- ment actions. This study, along with previous surveys provides information on species biology that will help assess threats and recovery needs. Spiranthes diluvialis is restricted to low- elevation valleys. In Montana, it is further restricted to specialized valley bottom soil and hydrology conditions, in habitat that is altered or fragmented by agriculture. Previous spe- ciesi monitoring studies suggested downward trends under most land uses and settings (Arft 1 995). We hypothesized that the same vulner- ability if not trends, exists in Montana. Ute ladiesi-tresses {Spiranthes diluvialis) is a long-lived perennial with a flowering stalk arising from clusters of basal leaves and short, tuberously thickened roots. The species reproduces strictly by seed. The flowers are protandrous (i.e., with staggered development of the male and female organs in each flower), and are pollinated by bumblebees (Sipes and Tepedino 1995). Flower- ing and vegetative growth forms are illustrated in Figures 2 and 3. In Montana, most vegetative plants have one-to- few basal leaves but may have as many as seven. Vegetative plants that we studied ranged mostly from 3-8 centimeters in height, though in 1 998, a poor-flowering year, some vegetative plants produced leaves only 1 centimeter in length. Flowering lasts at least three weeks in August with typically 9-17 flowers [4-25] per inflorescence. The species is highly palatable, and we often found browsed plants, even when the surrounding grass was not touched. Figure 1. Illustration of 5/7/ra^^/z^^ diluvialis by Carolyn Crawford Figure 2. Spiranthes diluvialis in flower Figure 3. Spiranthes diluvialis in vegetative stage 2 In any given year, mature plants are in flower- ing, non-flowering (vegetative) and seasonally dormant stages (persisting belowground; Lesica and Steele 1994). The species can be reliably located only when it is flowering, unless other vegetation cover and thatch are removed or precise locations are recorded to relocate vegetative plants. To monitor a species in which only one of three mature life history stages can be reliably located requires extended monitoring to map vegetative plants and determine the mean duration of seasonally dormant plants. Thus, repeated years of monitoring are needed to establish base population numbers. Previous researchers determined that mature plants do not remain in a vegetative state for more than one year (Arft 1 995b, Riedel et al. 1 995), but the unknown duration of seasonal dormancy has not been determined. A simplified life history diagram is presented below (Figure 4). The thick tuberous roots depend on mycorrhizal fungi for enhanced water and nutrient absorption, as do other members of the Orchid Family (Wells 1981). Another species of Spiranthes has been shown to persist for up to nine years as an imma- ture subterranean parasite or symbiont, before producing aerial shoots (Tamm 1972). Thus, it is possible that there are subterranean stages of immature as well as mature Spiranthes diluvialis plants. No juvenile plants were observed during the course of this monitoring study, and we did not consider immature plants for all practical pur- poses. These are the same categories used in the previous monitoring studies (Arft 1995, Riedel et al. 1995) except that the other studies included a class of flowering plants in which an inflorescence formed but did not set any fruits. This phenomenon was absent in Montana, though sometimes the latest and youngest fruits on some inflorescences aborted. Figure 4. Life History oi Spiranthes diluvialis Vegetative Plant Flowering Plant In the previous monitoring study, the flowering stage was identified as the most critical stage of hfe history in mature plants. Early-season haying and grazing, and vole herbivory of the inflorescences, at least under grazed and mown conditions, were identified as a major limit to reproductive success. We did not follow the species over the course of the growing season but have growing season information from Colorado for background (Arft 1 995). In June the plants emerge. They flower in July, up to a month earlier than in Montana. They produce an over wintering rosette in late summer. Habitat and Study Site Throughout much of its range, Spiranthes diluvialis occupies mid-seral riparian habitat, and may depend on some degree or frequency of habitat disturbance (Arft 1995, U.S. Fish and Wildlife Service 1995). The species occurs in meandered wetlands at low elevations in open valley bottom settings. In Montana, Spiranthes diluvialis habitat occu- pies a delta-like setting of meandered wetlands where there is consistently a shallow water table, calcareous soils, and gravelly alluvium at or near the rooting zone that is saturated in spring and remains moist through the growing season. These areas are not and were not linked to active alluvial processes but offer a low-competition setting. Valley soils immediately above and surrounding the meandered wetlands are classified as salt-affected wetland soils; they include fine, silty mixed aquic calciorthids and fine, loamy mixed fiuvaquents or fluvaquentic haploboroUs. The status report provides more detailed description of Spiranthes diluvialis habitat soils, and the Madison County soils survey (Boast and Shelito 1 989) provides more detailed descriptions of the surrounding soils. The surrounding salt-loving and salt-tolerant vegetation near Spiranthes diluvialis wetlands is dominated by alkali sacaton (Sporobolus airoides). Other species that are often present in or near the wetlands include buffaloberry (Shepherdia argentea), greasewood (Sarcobatus vermiculatus) and inland saltgrass (Distichilis striata). Speciesi vegetation in Montana is also described in much greater detail in the status report (Heidel 1 998.) The shallowness of the soil indicates a slow rate of soil buildup and slow successional process, which may account for the ability of Spiranthes diluvialis to persist. Many of these wetlands have areas of marl accumula- tion, and indeed, Lewis and Clark avoided walking the valley bottoms to avoid the risk of entering ibogsi (Nell and Taylor 1996). Disturbances such as bison grazing and fire may have historically helped maintain the low- competition habitat required by this species. Our monitoring site is the first documented Montana locality for Spiranthes diluvialis, a typical meandered wetland setting. The depth of the basin is less than 1 meter, and it is surrounded by salt-affected soils dominated by alkali sacaton (Sporobolus airoides) with widely scattered buffaloberry (Shepherdia argentea.) At the monitoring site, Spiranthes diluvialis is restricted to the irregular margins of the wetland, where the vegetation cover is relatively tall and dense compared to other sites, comprised of species like plains reedgrass (Calamagrostis inexpansa), clustered field sedge (Carexpraegracilis), and bearded wheatgrass (Elymus trachycaulus). »' -^.m Jh--.W K il M Figures. Study Site In other sites, short-stature graminoids like copycat sedge (Carex simulata) and few- flowered spikerush {Eleocharis pauciflora) assume a great or greater dominance. The study site is part of a small pasture with a history of livestock grazing, usually in early summer. The practice of early summer grazing continued during this study. In 1 997, cattle were not removed until after flowering had started, and a high incidence of herbivory was noted. Fire was a common tool of tribes in the headwaters area to manipulate bison move- ment (Nell and Taylor 1 996). An arson flre took place at the monitoring site in January 200 1 and burned the entire occupied habitat. The field visit in August indicated that the fire thoroughly burned the uplands but in the wetland it left the thatch and litter partially bumed, with stubble standing. Light snow cover or slight topographic relief may have reduced the effects of the bum in the wetland. The fire-prone climate of Spiranthes diluvialis habitat is characterized by a hot drought period. This also coincides with fiowering time in the latter half of summer, as shown at the most similar weather monitoring station at Twin Bridges, MT. Figure 6. Climate of Twin Bridges Methods The monitoring plot was established in 1 996 to track the entire population, one that is restricted to a single wetland basin and falls within an area of about 20 X 30-meters (Heidel 1 998). One-meter rebar stakes pounded to within 0.3 -meters of the surface were used to mark the four outer comers of the plot, except that the northem stakes fell 2- meters short of the maximum population extent. All rebar were placed in shrubs to be inconspicuous and avoid interference with livestock movement and visitors. The plot was mapped out with X & Y coordinates using a 30-meter tape along the southem bound- ary as the iX axisi (facing north), and another along the northem boundary to ensure consistent orientation of the lY axisi between tapes. A single tape was moved along the i Y axisi from left to right (west to east) and meter sticks were used to delimit 1 x 1 -meter areas. Individual plants were mapped within each subplot to at least 0. 1 -meter accuracy. The population was concentrated in relatively narrow bands along the wetland margin requiring care to avoid Twin Bridges, MT (1421 m/4660 ft) (6.1 C/43.0 F) (245.6 mm/9.7 in) (1948 -1999) Temperature Precipitation This diagram shows average monthly temperature and precipitation. The growing season length is the number of frost-free days, i.e., with mean daily minimum temperature above 0° C. 5 trampling plants when moving up the i Y axisi. For flowering plants, the numbers of buds (un- opened flowers; B), open flowers (F), and fruits (R), and any aborted fruits (A) were recorded per flowering stem. Stems closer than 2-centimeters were treated as shoots from the same plant; paired flowering stems were uncommon and noted as such for vegetative plants, and the total number of basal leaves was recorded. We also noted any browsing (b) or trampling (t) of flowering stems or basal leaves. Monitoring began during the middle of flowering in 1996, but moved to the end of the flowering period in all following years in order to gather data on seed set and avoid damaging shoots that had not bolted. This nearly eliminated data on buds, replacing it with data on fruits and aborted fruits for fecundity analysis. In general, flowering plants that were browsed were still discernible. We used monitoring methods that were compa- rable to previous monitoring studies of Arft (1 995) and Riedel et al. (1 995), with one exception. In an effort to avoid undue attention to the plants we did not tag plant locations along a heavily traveled public road. We used the same life history catego- ries except we did not have a category to repre- sent those flowering plants that did not set fruit. This phenomenon was not present in the study area (discussed previously). The Arft study had the added benefit of tracking plants throughout the growing season so that any herbivory or other losses were more easily identified as such. Results and Discussion Monitoring results provide a basis for interpreting the status survey results in Heidel (1 998). We developed a formula for extrapolating population counts of flowering stems to actual population estimates, including vegetative and seasonally dormant (underground) plants. If the total number of plants that flowered during the five-year moni- toring period (total=204) represents the best estimate of population size, then the number of plants that flower in any given year represents the proportion of flowering/nonflowering [vegetation + seasonally-dormant] plants. The flowering stem number counts ranged from 1 1-95 plants, i.e., 5% - 46% of the estimated total population number. Even in a igoodi flowering year, just over half of the plants cannot be reliably located because they are belowground or inconspicuous among thatch and taller vegetation cover. Using the 2X factor as a conservative basis for extrapolation, the estimates of 1,574 plants tallied from all twelve presently known populations in Montana represent a total of at least 3,148 plants in the state. Most of the population estimates were made during survey that took place in 1997. At the monitoring site in 1997, only 18% of the plants flowered (36 out of 204). If we adjust statewide estimates using a 5X factor as a more realistic basis for extrapolation, there are at least 7,870 plants in the state. Whichever estimate is used to adjust survey numbers, the total number of Spiranthes diluvialis plants in all Montana populations is less than the estimates for a couple of the largest populations in states to the south. This might be expected because most of the habitat in Montana occurs in highly interrupted linear bands rather than in semi- continuous river corridor bands or broad meadows. These interpretations are based on several assumptions. By using the tally of 204 plants at the monitoring site as representing total population size, we assume that all of the plants flowered at least once during the five- year period, and that there was no mortality. In extrapolating population numbers through- out Montana based on this data, we also assume that different populations have similar proportions of plants flowering. The data also indicate that population esti- mates and even presence/absence determina- tions in ipoori years have marginal merit, and actual populations are likely to be higher than estimates using flowering-plant counts from these years. Survey results during a poor year are almost always preliminary, and a postponement or extension of survey to the following year is preferable whenever it is possible. Thus, June monthly rainfall and temperature conditions should be reported with any survey results noting their difference from the mean. Exceptionally cool, wet years are to be avoided for Section 7 consultation surveys for Spiranthes diluvialis whenever possible, a term that is appropriate to add to recommended Section 7 guidelines in Montana (Heidel 2000). This study provides evidence that flowering patterns shift with microhabitat between years. At our monitoring site, Spiranthes diluvialis was restricted to wetland margins within a 2-3 meter band. Some places of the wetland consistently had flowering plants, but there were often different patterns of flowering plant distribution in comers of the wetland and at different positions on the margin fi-om year to year. Life History and Trend Monitoring results show flowering levels varied by nearly one order of magnitude from year to year (1 1-95 flowering plants in 1999 and 1998, respectively; Figure 7.) Plants can only be tracked once they have flowered. In the past three years, the number of inewi plants has leveled off, indicating that we have documented the majority of plants. The most favorable year for flowering during the monitoring period occurred in 1998, and by the third year of monitoring, we had documented 86% of the plants that flowered within the five-year period. In general, the speciesi best flowering years seem to correspond with extreme heat during flowering. This is revealed in a review of the five years of climate data from the nearest monitoring station of similar habitat at Twin Bridges. Preliminary review of the climate data also indicates that growing seasons that start out as relatively cold and wet, as indicated by mean June values, correspond with low flowering levels. For species that remain dormant throughout one or more growing seasons, trend cannot be determined until the average number of years is calculated in which the plant is dormant Figure 7. Monitoring overview of Spiranthes diluvialis 250 1 200 S Z 150 100 50 1996 1997 1998 1999 2000 ■ dormant/dead plani ■ vegetative plants D flowering plants* (Lesica and Steele 1 994). Therefore, our data do not provide adequate basis for evaluating popula- tion trend and critical life history stages. Most species that exhibit the seasonal dormancy phe- nomenon do not remain dormant for more than one growing season, with the exception of many members of the Orchid Family (Lesica and Steele 1994). In this study, the first year of monitoring in 1 996 located almost 25% of all plants that were found to flower over the course of the five-year monitor- ing period (50 plants). Of the ones that went dormant in 1 997, about half of these ended their dormancy between 1 998-2000 and had a mean dormancy duration of 1 .6 years. Of the ones that went dormant for the first time in 1 998, only 24% ended their dormancy by 2000 and had a mean dormancy duration of two years. This demon- strates that the mean length of season-long dor- mancy is a multi-year value of at least two years in Montana. Both sets of data are graphed in Figure 8. Two years of lead-time is needed to evaluate the duration of season-long dormancy so we were limited to a 3 -year period for evaluating its dura- tion. It would be necessary to extend this study for at least two more years to quantify the average dormancy duration, and then evaluate trend using a t-test or stage-based transition matrices. It is possible that the viability projections run for Spiranthes diluvialis in Colorado, based on three years of monitoring data (Arft 1995), included assumptions that season-long dormancy does not last more than one year. In any case, the three years of data from the Colorado study sites are inadequate for making projections without know- ing more about the duration of dormancy. Viability projections should be re-run with documented season-long dormancy values derived in the region or modeled values. Unlike the dormancy stage, the average length of the flowering and the vegetative stages of Spiranthes diluvialis at the study site are little more than one year. Prolonged dormancy is often associated with environmental stress (Rabotnov 1969), particularly episodes of drought among terrestrial plants. In some wetland species, prolonged dormancy is associated with prolonged inundation. The latter may also apply to Spiranthes diluvialis, since the rooting zone remains saturated long into the growing season. Comparison with Other Monitoring Studies The monitoring site in Jefferson County, Montana is representative of speciesi habitat at the northern limits of the speciesi range, east of the Continental Divide. Warning signs such as decline in populations, fruit set problems and other damages that were noted in the Colorado and Utah monitoring studies (Arft 1 995, Riedel et al. 1 995) were not confirmed in this study: ■ We did not detect decline in popula- tion numbers even if we assume that seasonal-long dormancy lasts for only one year. ■ We did not find evidence of fruit set problems. Instead, we found high fruit set and observed bumblebees selec- tively pollinating the species in spite of its relatively small flowering plant numbers. ■ We did not find direct signs of damage that were proven or suspected of causing mortality. Most plants with browsed infiorescences or leaves were found to survive in later years. There were no signs of rodent activity in the particular habitat occupied by the species (runways and tunnels), indicating that vole herbivory seemed an unlikely limit on reproductive success. It is possible that this population is less vulner- able under existing land management practices and environmental conditions than larger populations 8 Figure 8. Dormancy duration of Spiranthes diluvialis Dormancy duration of Spiranthes diluvialis (0 o 80 70 60 50 40 30 20 10 4 D Hants first dormant in 1997 ■ Rants first dormant in 1998 1998 1999 2000 Year in which dormancy ended remained dormant Figure 9. Vegetative stage duration of Spiranthes diluvialis Vegetetative stage duration of Spiranthes diluvialis U) c •a C 0) O G) v> JS - (0 iS d) Q. o M- > o ^ n Rants first vegetative in 1997 ■ Rants first vegetative in 1998 1998 1999 2000 Year in which veg. stage ended remained vegetative Figure 10. Flowering stage duration of Spiranthes diluvialis Flo>A/ering stage duration of Spiranthes diluvialis S 0) o I 1 n Rants first flowering in 1996 ■ Rants first flowering in 1997 1 1 ^ 1996 1997 1998 IS Year in which flowering stage ended 2000 monitored in the center of its range. The popula- tion is not necessarily invulnerable, and we note that there is almost no protection of the species under the Endangered Species Act in Montana because it does not occur on federal lands and is scarcely affected by federal actions (Heidel 1 998.) Guide to Future Management Action The flowering stage is readily impacted by man- agement actions, and the infloresences represent large, sporadic investments of resources that are highly accessible to herbivores and highly palat- able. The flowering stage is a vulnerable stage, even though we were not able to determine which life history stage is the most limiting in speciesi viability. We echo the management recommenda- tions to come out of the Arft (1 995) research, i.e., to avoid removing flowering stalks under grazing or mowing by a shift in timing that avoids removal of the inflorescence after it bolts or before seeds disperse. We did not identify new threats. The invasion of noxious weeds near and into species habitat poses a direct threat to the species through habitat degradation and the potential impact of herbicides. Further consultation or research is needed to evaluate the influence of broadleaf herbicides on this species. The lack of experimental controls or robust baseline provided an inadequate basis to evaluate grazing practices or the recent arson Are. The inadvertent delay in moving livestock in 1997 confirmed that cattle selectively graze infiorescences. The persistence of this species in relatively high vegetation cover and tall- stature vegetation cover at the particular monitoring site may in fact be linked to the long-standing grazing regime. Continuation of current grazing practices is recommended, in concert with noxious weed control. Grazing appears to be a viable option for annual or periodic reduction of competing vegetation in such settings. If there is folio wup to the draft recovery plan (U.S. Fish and Wildlife Service 1995), and development of Riparian/Aquatic Habitat Management Objectives (RMOs) across its range or Standards and Guidelines for south- western Montana, then it will be necessary to address grazing, weed management, fire, and groundwater fiow. An intensive demographic monitoring baseline that tracks individual plants and quantifies the season-long dor- mancy stage of life history is recommended for any management changes in Montana that are prompted by conservation, in order to gauge the effectiveness of guidelines and recovery efforts. 10 Literature Cited Arft, A. M. 1 995a The genetics, demography, and conservation management of the rare orchid Spiranthes diluvialis. PhD thesis. University of Colorado, Boulder. 170 pp. Boast, R. R. and R. G. Shelito. 1989. Soil survey of Madison County Area, Montana. USDA Soil Conservation Service, Bozeman, MT. 384 pp. Heidel, B. 1 996. New additions to the Mon- tana flora. Madrono 43(3): 436-440. Heidel, B. 1998. Conservation status of Spiranthes diluvialis in Montana. Report to U.S. Fish and Wildlife Service. Montana Natural Heritage Program, Helena. 55 pp. Heidel, B. 2000. A framework for Section 7 consultation m\o\\mg Spiranthes diluvialis in Montana. Lesica, P. and B. M. Steele. 1994. Prolonged dormancy in vascular plants and implications for monitoring studies. Natural Areas Journal 14(3):209-212. Rabotnov, T. A. 1 969. On coenopopulations of perennial herbaceous plants in natural coenoses. Vegetation 19:87-95. Riedel, L., S. Petersburg and T. Naumann. 1995. Spiranthes diluvialis monitoring and habitat restoration, 1995 update, Dinosauer National Monument, National Park Service. 6 pp. Sipes, S. D. and V. J. Tepedino. 1995. Reproduc- tive biolog of the rare orchid, Spiranthes diluvialis: breeding system, pollination, and implications for conservation. Conser- vation Biology 9(4):929-938. U.S. Fish and Wildlife Service. 1992. Endangered and threatened wildlife and plants; final rule to list the plant Spiranthes diluvialis (Ute ladiesi-tresses) as a threatened species. Federal Register 57(12):2048- 2054. U.S. Fish and Wildlife Service. 1995. Ute ladiesi- tresses {Spiranthes diluvialis) recovery plan ft agency review draft. 46 pp. 11 APPENDIX A. Global and State Rank Guidelines The term ispecies of special concerni includes taxa that are rare, endemic, disjunct, threatened or endan- gered throughout their range or in Montana, vulnerable to extirpation from Montana, or in need of further research. The term also encompasses species that have a special designation by organizations or land management agencies in Montana, including: Bureau of Land Management Special Status and Watch species; U.S. Forest Service Sensitive and Watch species; U.S. Fish and Wildlife Service Threatened, Endangered and Candidate species. Taxa are evaluated and ranked by the Heritage Program on the basis of their global (range-wide) status, and their statewide status according to a standardized procedure used by all Natural Heritage Programs. These ranks are used to determine protection and data collection priorities, and are revised as new infor- mation becomes available. For each level of distributionoglobal and stateospecies are assigned a numeric rank ranging from 1 (critically imperiled) to 5 (demonstrably secure). This reflects the speciesi relative endangerment and is based primarily on the number of occurrences of that species globally or within the state. However, other information such as date of collection, degree of habitat threat, geographic distribution patterns and population size and trends is considered when assigning a rank, and the number of occurrences listed below are suggestions, not absolute criteria. For example. Clustered ladyis slipper (Cypripedium fasciculatum) is ranked G4 S2. That is, globally the species is apparently secure, while in Montana it is imperiled because of rarity, or because of other factors making it demonstrably vulnerable to extirpation. For ranks, substitute S (State) or G (Global) in these definitions Rank Definition 1 Critically Tmperiledo Critically imperiled because of extreme rarity or because of some factor(s) making it especially vuhierable to extirpation. Typically 5 or fewer occurrences c very few remaining individuals (< 1,000). 2 Imperiledo Imperiled because of rarity or because of some factor(s) making it very vuhierable to extirpation. Typically 6 to 20 occurrences or few remaining individuals (1,0( to 3,000). 3 Vulnerableo Vuhierable either because rare and uncommon, or found only in a restricted range (even if abundant at some locations), or because of other factors making it vulnerab) to extirpation. Typically 21 to 100 occurrences or between 3,000 and 10,000 individuals. 4 Apparently Secureo Uncommon but not rare, and usually widespread. Possible cause of long-term concem. Usually more than 100 occurrences and more than 10,000 individuals. 5 Secureo Common, widespread, and abundant. Essentially ineradicable under present conditions. Typically with considerably more than 100 occurrences and more than 10,000 individuals. ^Qualifiers and Rank Ranges'^ Qualifier Definition ## Range Ranko A numeric range rank (e.g., S2S3) is used to indicate the range of uncertainty about the exact status of the element. Ranges cannot skip more than one rank (e.g., SU is used rather than S1S4). 9 Unrankedo rank not yet assessed. # A modifier to X or H; the species has been reintroduced but the population is not yet estabhshed. it G or S rank has been assigned and is under review. Contact the individual state Natural Heritage program for assigned rank. HYB Hybrido Element not ranked because it represents an interspecific hybrid, not a species. U Unrankableo Currently unrankable due to lack of information or due to substantially conflicting information about status or trends. E Exotico An estabhshed exotic; may be native in nearby regions (e.g., house finch or catal in eastern U.S.). E# Exotic Numerico An estabhshed exotic that has been assigned a numeric rank to indicate its status, as defined for Gl or SI through G5 or S5. A Accidentalo Accidental or casual, in other words, infrequent and outside usual range. Includes species (usually birds or butterflies) recorded once or only a few times at a location. A few of these species may have bred on the one or two occasions they were recorded. Examples include European strays or western birds on the East Coast and vice- versa. B Breedingo Basic rank refers to the breeding population of the element. C Captive or Cultivatedo Native element presently extant only in captivity or cultivation. H Possibly Extirpated (Historical)© Element occurred historically, and there is some expectation that it may be rediscovered. Its presence may not have been verified in the pas 20 years. An element would become GH or SH without such a 20-year delay if the only known occurrences were destroyed or if it had been extensively and unsuccessfully lookec for. Upon verification of an extant occurrence, GH or SH-ranked elements would typicall) receive a Gl or SI rank. The GH or SH rank should be reserved for elements for which some effort has been made to relocate occurrences, rather than simply using this rank for e elements not known from verified extant occurrences. N Nonbreedingo Basic rank refers to the non-breeding population of the element. P Potentialo Potential that element occurs but no extant or historic occurrences are accepts R Reportedo Element reported but without a basis for either accepting or rejecting the repo or the report not yet reviewed locally. Some of these are very recent discoveries for which the program hasn't yet received first-hand information; others are old, obscure reports. T Rank for subspecific taxon (subspecies, variety, or population); appended to the global rar for the full species, e.g. G4T3 X Presumed Extirpatedo Element is believed to be extirpated. Not located despite intensiv searches of historical sites and other appropriate habitat, and virtually no likelihood that it will be rediscovered. CRITERIA USED FOR RANKING The criteria for ranking are based on a set of quantitative and qualitative factors. These factors are listed below in order of their general importance: a. Number of Element Occurrences (EOs) : the estimated number of EOs throughout the Elementis global range; b. Abundance: the estimated global abundance of the Element (measured by number of individuals, or area, or stream length covered); c. Size of Range: the estimated size of the Elementis global range; d. Distribution trend: the trend in the Elementis distribution over its global range; e . Number of protected EOs : the estimated number of adequately protected EOs throughout the Elementis global range; f. Degree of threat: the degree to which the Element is threatened globally; g. Fragility: the fragility or susceptibility of the Element to intrusion; h. Other global considerations: for example, the quality or condition of EOs that affect or may affect endangerment status; unexplained population fluctuations; reproductive strategies that are dependent on specific habitat; etc.